Photographic development apparatus

Abstract

Apparatus for processing rectangular sheets of photographic material in varying format sizes is equipped to calculate at least approximately the surface area of the sheets fed therethrough. For this purpose, the apparatus includes a sensor for determining a dimension, e.g. the length, of each sheet, a memory for storing the length and width dimensions of a plurality of sheet format sizes, and a control unit which compares the determined dimension of a sheet with the dimensions stored in the memory and upon finding a match therebetween gives an output signal indication of the surface area of the sheet. If more than one match is found, the unit gives an output signal corresponding to the largest format size having a dimension equal to the determined dimension. If no match is found by the control unit, the unit is adapted to give an output signal equal to the multiple of the determined dimension and the largest of the stored width dimensions or, alternatively, an output signal corresponding to a format size having a length greater than the determined dimension. The surface area indications can be used to regulate the replenishment of processing liquid consumed during processing.

We claim: 
     
       1. In an apparatus for the processing of generally rectangular sheets in a plurality of different format sizes of exposed photographic material in which said sheets of material are fed one at a time through the apparatus, the improvement of means for substantially calculating the surface area of said sheet material being processed, which means comprises a sensor for determining one linear dimension of each sheet of the material being fed, memory means for storing the length and width dimensions of a plurality of given format sizes of rectangular sheets of said material to be processed in the apparatus, and control means for comparing the dimension determined by said sensor with said stored dimensions and producing a signal indicative of a surface area of a stored format size when there is a match between one of said stored dimensions and said determined dimension, said control means in the event said sensor determines a dimension which is substantially the same as a stored dimension for more than one of said format sizes, producing a signal indicative of the largest sheet format size containing said dimension. 
     
     
       2. Apparatus as claimed in claim 1, in which said sheets of material are fed through at least one region thereof at a generally constant velocity and said sensor is arranged in said region. 
     
     
       3. Apparatus as claimed in claim 1, wherein the apparatus further includes a sheet feed means for feeding said sheets along a generally longitudinal path, and a feed sensor which senses when a sheet of said material is substantially centered relative to the axis of said path, the feed sensor being operable to prevent the operation of the feed means if the presence of a sheet is not sensed by said feed sensor. 
     
     
       4. Apparatus as claimed in claim 1, wherein said sheets of material are fed in the apparatus though at least one bath of processing liquid subject to at least one process parameter and which further comprises at least one further sensor each such further sensor sensing the existence of a process parameter in the apparatus and sheet feed means for feeding the sheets of said material, said feed sheet means being driven through a clutch means, each of said further sensors being operable to disengage said clutch means and render the sheet feed means inoperable if the existence of said process parameter has not been sensed. 
     
     
       5. Apparatus as claimed in claim 1, wherein said photographic sheet material is an aluminum lithographic offset printing plate. 
     
     
       6. In an apparatus for the processing of generally rectangular sheets in a plurality of different format sizes of exposed photographic material in which said sheets of material are fed one at a time through the apparatus, the improvement of means for substantially calculating the surface area of said sheet material being processed, which means comprises a sensor for determining one linear dimension of each sheet of the material being fed, memory means for storing the length and width dimensions of a plurality of given format sizes of rectangular sheets of said material to be processed in the apparatus, and control means for comparing the dimension determined by said sensor with said stored dimensions and producing a signal indicative of a surface area of a stored format size when there is a match between one of said stored dimensions and said determined dimension, said control means in the event there is no match between the stored dimensions and said determined dimension, multiplying the determined dimension by the largest of the stored width dimensions and producing a signal indicative of a surface area corresponding to such multiple. 
     
     
       7. Apparatus as claimed in claim 6, in which said sheets of material are fed through at least one region thereof at a generally constant velocity and said sensor is arranged in said region. 
     
     
       8. Apparatus as claimed in claim 6, wherein the apparatus further includes a sheet feed means for feeding said sheets along a generally longitudinal path, and a feed sensor which senses when a sheet of said material is substantially centered relative to the axis of said path, the feed sensor being operable to prevent the operation of the feed means if the presence of a sheet is not sensed by said feed sensor. 
     
     
       9. Apparatus as claimed in claim 6, wherein said sheets of material are fed in the apparatus through at least one bath of processing liquid subject to at least one process parameter and which further comprises at least one further sensor each such further sensor sensing the existence of a process parameter in the apparatus and sheet feed means for feeding the sheets of said material, said feed sheet means being driven through a clutch means, each of said further sensors being operable to disengage said clutch means and render the sheet feed means inoperable if the existence of said process parameter has not been sensed. 
     
     
       10. Apparatus as claimed in claim 6, wherein said photographic sheet material is an aluminum lithographic offset printing plate. 
     
     
       11. In an apparatus for the processing of generally rectangular sheets in a plurality of different format sizes of exposed photographic material in which said sheets of material are fed one at a time through the apparatus, the improvement of means for substantially calculating the surface area of said sheet material being processed, which means comprises a sensor for determining one linear dimension of each sheet of the material being fed, memory means for storing the length and width dimensions of a plurality of given format sizes of rectangular sheets of said material to be processed in the apparatus, and control means for comparing the dimension determined by said sensor with said stored dimensions and producing a signal indicative of a surface area of a stored format size when there is a match between one of said stored dimensions and said determined dimension, said control means in the event there is no match between the measured dimension and a stored dimension, said control means giving an indication of a surface area corresponding to a sheet material having a format with a length dimension larger than the determined dimension. 
     
     
       12. Apparatus as claimed in claim 11, in which said sheets of material are fed through at least one region thereof at a generally constant velocity and said sensor is arranged in said region. 
     
     
       13. Apparatus as claimed in claim 11, wherein the apparatus further includes a sheet feed means for feeding said sheets along a generally longitudinal path, and a feed sensor which senses when a sheet of said material is substantially centered relative to the axis of said path, the feed sensor being operable to prevent the operation of the feed means if the presence of a sheet is not sensed by said feed sensor. 
     
     
       14. Apparatus as claimed in claim 11, wherein said sheets of material are fed in the apparatus through at least one bath of processing liquid subject to at least one process parameter and which further comprises at least one further sensor each such further sensor sensing the existence of a process parameter in the apparatus and sheet feed means for feeding the sheets of said material, said feed sheet means being driven through a clutch means, each of said further sensors being operable to disengage said clutch means and render the sheet feed means inoperable if the existence of said process parameter has not been sensed. 
     
     
       15. Apparatus as claimed in claim 11, wherein said photographic sheet material is an aluminum lithographic offset printing plate. 
     
     
       16. Apparatus for the development of exposed photographic sheet material according to certain desired process parameters, said apparatus including a sheet feed means for feeding material into the apparatus, the sheet feed means being driven through a clutch means, and at least one sensor each such sensor sensing a process parameter and controlling said clutch means so that the feed means is operable only when the desired processing parameter is sensed by each such sensor.